Fig. 8: Middle Ordovician geochronology10, conodont biostratigraphy13, palaeoclimate5 and biodiversity1,31.

The astronomical tuning and conodont richness added by the current study is marked in purple. The astronomical timescale is anchored in the high-precision zircon U/Pb date of 467.5 ± 0.28 Ma10. Sketched palaeoclimate trends highlight several punctual cooling episodes in the Dapingian coolhouse before the major Darriwilian cooling. The global onset of the GOBE coincides with regional richness spikes across clades and facies belts. Note that the asteroid breakup is well-constrained7,10 and postdates both palaeoclimatic and biotic events.